1. Field of the Invention
This invention relates generally to a passenger vehicle occupant restraint system having an air bag module and, more particularly, to an air bag module having direct venting.
2. Background Art
Occupant restraint systems employing air bag modules are well known. During a collision of a predetermined magnitude, an air bag cushion is inflated by an inflator and is deployed in the vehicle for protection of the vehicle occupant. The air bag cushion is deployed at a high rate of speed and force optimized to protect a wide range of occupants under various conditions. There are, however, times when deploying an air bag cushion is not desirable, such as when a vehicle occupant is so close to the air bag that normal deployment of the air bag may cause injury to the occupant. An occupant that is too close to the air bag is said to be out of position. Various air bag module designs have been developed to reduce the amount of pressure and force caused by an air bag deployment to an out of place vehicle occupant. For example, some systems use vents on the air bag cushion that open and release gases generated by the inflator as the bag is deploying. However, these systems only control the rate and amount of inflation of the air bag cushion in a predetermined manner, but do not do so in response to the position of the occupant.
Another system disclosed in U.S. Pat. No. 6,206,408 uses vents on the air bag canister side wall that are initially open and slidingly close if no force is exerted on the deployment door. If force is exerted onto the deployment door, the vents remain open and the gas is vented therethrough, thereby thwarting deployment of the air bag cushion. However, this device is exceedingly complicated to manufacture requiring sliding mechanisms.
It would be desirable to have an occupant restraint system employing an air bag cushion that does not fully deploy when an occupant is out of position that is of a simple design.